An existing water pump is described in Japanese Laid-open Patent Application 2004-116486.
The existing water pump has a pump housing having therein a pump chamber, a drive shaft rotatably supported in the pump chamber, a pulley connected to one end of the drive shaft through a discal end wall, a ball bearing provided between the pulley and the pump housing to rotatably support the pulley, an impeller connected to the other end of the drive shaft to integrally rotate therewith and a mechanical seal provided between the impeller and the pulley.
The discal end wall is formed with a plurality of through holes that are arranged in a circumferential direction at evenly spaced intervals. Each of the through holes has such functions as to allow insertion of a tool therethrough to press an outer race of the ball bearing onto an inner cylindrical surface of the pulley at the time of assembling the water pump and as to allow water leaked from the interior of the pump housing through the mechanical seal to be discharged to the outside.
In the existing water pump, however, the through holes are placed near the center of the discal end wall. Due to such placement of the through holes, the function as to allow discharging of leaked water through the mechanical seal to the outside becomes poor, and due to the leaked water poor discharging, it often occurs that foreign substances such as water, dust and the like that might enter the pump housing (in other words, enter the ball bearing) through the through holes are not easily discharged to the outside.
The present invention is provided by taking the actual situation of the hitherto used water pump into consideration and aims to provide a water pump that is improved in dischargeability of foreign substances such water, dust and the like to the outside through the through holes.